The present invention relates to novel compounds which can direct and control the growth and/or crystal phase of pigment particles. Such compounds are particularly useful when present during the synthesis or finishing of an organic pigment.
Dihydroquinacridones are intermediates for the production of the well known quinacridone pigments like C.I. Pigment Violet 19, C.I. Pigment Red 202 and C.I. Pigment Red 122.
A number of patents describe processes for the direct synthesis of pigments in a pigmentary form to avoid the additional expensive and oftentimes environmentally unfriendly pigment finishing processes (e.g. processes for particle size reduction and/or crystal-form modification). For example, European Patent No. 643,110 and U.S. Pat. No. 5,424,429 describe a direct synthesis of quinacridone solid solutions and 2,9-dichloroquinacridone in pigmentary form, respectively, in the presence of quinacridone phthalimidomethyl derivatives. European Patent No. 685,530 describes the direct synthesis of pigmentary grade dioxazine in the presence of a dioxazine derivative.
It is also known that sulfonic acid derivatives of certain pigments can effectively diminish the crystal growth during the isolation of the pigment from a reaction mixture. Such sulfonic acid derivatives are described, for example, in U.S. Pat. No. 3,386,843. Other patents describe the use of sulfonic acid derivatives of pigments to stabilize against recrystallization and change of crystal modification as, for example, in G.B. Patent No. 1,544,839 which is directed to phthalocyanine pigments.
U.S. Pat. No. 5,755,873 describes a method for the preparation of quinacridone pigments in which a quinacridone derivative is incorporated during synthesis and copending provisional application Ser. No. 60/087,773 describes a direct synthesis of pigmentary diketopyrrolopyrrole pigments in the presence of quinacridone or diketopyrrolopyrrole derivatives.
Although the addition of such known pigment derivatives can be advantageous, pigment synthesis in the presence of such derivatives in many cases does not provide the favored pigmentary crystal size, shape or crystal modification.
Copending U.S. Provisional Patent Application entitled xe2x80x9cPIGMENT PARTICLE GROWTH AND/OR CRYSTAL PHASE DIRECTORSxe2x80x9d, of the present inventor filed Feb. 2, 1999, discloses pigment particle growth and/or crystal phase directors which in many cases allow for the direct synthesis of pigmentary pigments without requiring a finishing step. However, these compounds themselves have coloristic properties and when used with certain pigments can behave as colored impurities and/or can reduce the saturation of the final pigment.
Japanese Patent No. 061 45 546 describes phthalimidomethyl dihydroquinacridones and the use thereof as pigment dispersants.
The present invention is based on the discovery that new, colorless or only slightly colored compounds derived from 6,13-dihydroquinacridone are effective pigment particle growth controller and crystal phase directors when present during the pigment synthesis or a pigment finishing step. They are particularly effective for quinacridone and diketopyrrolo pyrrole pigments.
Such 6,13-dihydroquinacridone derivatives can be prepared by simple synthesis procedures and offer the pigment manufacturer a means to prepare a pigment providing the preferred color characteristic without requiring an additional pigment finishing step.
Since other known particle growth inhibitors which are derived from pigment derivatives are strongly colored and often can behave as an impurity, the present 6,13-dihydroquinacridone derivatives are only slightly colored. Their presence will not particularly change the hue of the pigment. Furthermore, the present 6,13-dihydroquinacridones derivatives are non planar molecules. Based on the state of the art it is unexpected that non planar molecules can act as particle growth inhibitors and crystal phase directors for pigment crystals composed of planar organic pigment molecules. Thus, the inventive compounds allow the manufacturer to produce high performance, high chroma organic pigments in an economical and environmentally friendly manner and therefore, are of extreme commercial importance.
The present invention relates to novel compounds of formula I:
(MO3S)mxe2x80x94Qxe2x80x94[CH2xe2x80x94(X)xe2x80x94(Y)n]oxe2x80x83xe2x80x83(I)
wherein Q represents a 6,13-dihydroquinacridone moiety of formula II: 
wherein A and B each independently represent a substituent selected from H, F, Cl, C1-C3alkyl and C1-C3alkoxy. Preferably, substituents A and B each represent hydrogen.
M of formula I represents a metal cation, quaternary N cation or hydrogen, X represents an aromatic group or a cyclo hetero aliphatic group with at least one 5 or 6 atom ring or a hetero aromatic group with at least one 5 or 6 atom ring and which is not a phthalimido group; Y is a sulfonic or carboxylic acid or salt thereof, m and n independent of one of the other each are numbers from zero to 2.5, and o is a number from zero to 4, wherein m and o are not zero simultaneously.
The present invention is further directed to a process for the preparation of compounds of formula (I) and to the use thereof.
Preferably, m in formula I represents a number from zero to 2 and most preferably zero to 1; n represents preferably a number from zero to 2 and most preferably from zero to 1.2, and o represents preferably a number from zero to 2 and most preferably from zero to 1.5, wherein m and o are not zero simultaneously. The values for m, n and o are determined by analytical methods like mass spectrometry such as LCMS, GCMS or the matrix-assisted laser desorption ionization technique (MALDI).
The metal cation M of formula I is preferably sodium, potassium, calcium, magnesium or aluminum, and the quaternary N cation of formula I is an ammonium or an alkyl ammonium group.
Typically, the group X of the inventive compound of formula I is an aromatic group with a 5 carbon or a 6 carbon ring or a polycyclic group containing two to six fused 5 carbon and/or 6 carbon rings; a cyclo-hetero aliphatic group including at least one 5 or 6 atom ring or fused 5 and/or 6 atom rings, or a hetero aromatic group which is not a phthalimido group, containing a 5 or 6 atom ring or fused 5 and/or 6 atom rings, and in which there are 1 to 4 hetero atoms of N, S and/or O.
Suitable aromatic groups include, for example, phenylene, naphthalene, acenaphthylene, anthracene, phenanthrene, naphthacene, chrysene, pyrene or perylene. Preferably the aromatic group is phenylene, naphthalene, anthracene or pyrene, and most preferably the aromatic group is phenylene or naphthalene.
Cyclo-hetero aliphatic groups are, for example, pyrrolidine, imidazolidine, piperidine, piperazine or morpholine.
Appropriate hetero aromatic groups are, for instance, pyridine, pyrazine, pyrimidine, pyridazine, isoindole, quinoline, isoquinoline, carbazole, phenothiazine, benzimidazolone, benzothiazole, pyrrolo, imidazole or pyrazole.
The above exemplified aromatic, cyclo hetero aliphatic or hetero aromatic groups can optionally be substituted with one or more halogen, oxy, hydroxy, imino, amino and/or C1-C18alkyl groups, preferably C1-C3alkyl or C1-C3alkoxy groups.
Examples of the large number of such substituted cyclo hetero aliphatic or hetero aromatic groups are, for instance, toluene, ortho-, meta- or para-xylene, chlorobenzene, 1- or 2-methyinaphthalene or anthraquinone, barbituric acid, melamine, 1,3,7-trimethylxanthin, hydantoin, 2-methylbenzimidazole, 2,6,8-trihydroxypurine, 1,8-naphtosultam, o-benzoic acid sulfimide or 2,4-dihydroxyprimidine.
Commonly, the group Y is a carboxylic acid or a sulfonic acid group. Most preferably the group Y is a free sulfonic acid or a sodium, potassium, magnesium, calcium, aluminum, quaternary ammonium or alkyl ammonium salt thereof.
A further embodiment, as described more fully below, of the present invention is a process for the preparation of compounds of formula I, wherein:
a) the moiety Q is dissolved in concentrated sulfuric acid;
b) the intermediate X is added into the solution and dissolved at a temperature below 50xc2x0 C.;
c) para-formaldehyde is added at a temperature below 50xc2x0 C.;
d) and then is heated to a temperature from to 50 to 100xc2x0 C.; and
e) then isolated.
The inventive 6,13-dihydroquinacridone derivatives are prepared, for example, by reacting a 6,13-dihydroquinacridone moiety of formula II and the intermediate X, a substantial portion of which is the moiety of group X, with formaldehyde. Preferably the reaction is carried out in concentrated (95-98%) sulfuric acid. In one preferred method, the 6,13-dihydroquinacridone of the moiety Q is dissolved in concentrated sulfuric acid at a concentration of about 5 to 30 weight percent, most preferably about 10 to 20 weight percent at a temperature below about 50xc2x0 C., preferably at about 35 to 45xc2x0 C. The intermediate X is added to the 6,13-dihydroquinacridone solution at a temperature below about 50xc2x0 C., preferably at about 35 to 45xc2x0 C. and is also dissolved. Finally, the formaldehyde is added, preferably in the form of para-formaldehyde, at a temperature below about 50xc2x0 C., more preferably at about 35 to 45xc2x0 C. The reaction mixture is heated to a temperature from about 50 to 100xc2x0 C. and stirred at that temperature until the reaction is complete, preferably for about 30 minutes to 6 hours, most preferably from about 30 to 90 minutes, and drowned into ice water. The resulting slurry is stirred for about 5 minutes to 6 hours, preferably from about 30 minutes to 3 hours, at a temperature of from about 0 to 50xc2x0 C., preferably from about 10 to 25xc2x0 C. The inventive 6,13-dihydroquinacridone derivatives are then isolated by filtration or centrifugation and are preferably washed with water. The resulting product cake can be dried or can be used in the form of an aqueous cake as an additive during the pigment synthesis.
In general, a stochiometric amount of the 6,13-dihydroquinacridone moiety of formula II, intermediate X and formaldehyde are used; however, an excess of the intermediate X or formaldehyde may be used to achieve the desired product. Preferably, the molar ratio of the 6,13-dihydroquinacridone:intermediate X:formaldehyde is 1:1 to 1.2:1 to 2.
If a high degree of sulfonation is desired, the reaction mixture is stirred at higher temperature, for example above 60xc2x0 C. If it is desirable to have a low degree of sulfonation, the reaction is maintained at lower temperature, for example below 60xc2x0 C.
The isolated samples can be analyzed by known methods, for example, by elementary analysis or mass spectrometry such as LCMS, GCMS or the matrix-assisted laser desorption ionization technique (MALDI) or by the HPLC method, all of which are well known to those of ordinary skill in the art. By the above preferred technical preparation method, which does not include specific cleaning steps, the purity of the isolated product is generally not 100% and the product contains, depending on the starting materials and reaction temperature, some remaining starting materials or other byproducts which, when in concentrations that do not impact the effect of the particle size and phase director, are tolerated and can actually provide additional advantageous effects. By technically well known methods, such as solvent treatments, recrystallization or precipitation from basic polar solvent solutions, for example in basic dimethyl sulfoxide or dimethyl formamide, such products can be further purified, if desired.
Generally, the inventive 6,13-dihydroquinacridone derivatives are added at a concentration of about 0.1 to 15 percent, preferably about 0.3 to 10 percent and most preferably about 0.5 to 8 percent by weight, based on the weight of pigment to be synthesized. The inventive 6,13-dihydroquinacridone derivatives can be added before or during the final pigment synthesis step.
The inventive 6,13-dihydroquinacridone derivatives are suitable as an additive for the synthesis of pigments of several pigment classes including pigments of the anthraquinone, phthalocyanine, perinone, perylene, diketopyrrolopyrrole, thioindigo, iminoisoindoline, iminoisoindolinone, quinacridone, flavanthrone, dioxazine, indanthrone, anthrapyrimidine and quinophthalone pigment class. The said derivatives are particularly suited for pigments of various pigment classes having different shades because they themselves are only slightly colored and therefore, the presence of the inventive compounds does not lower the saturation or change the hue of the pigment.
The inventive 6,13-dihydroquinacridone derivatives are especially suitable for the synthesis of direct pigmentary diketo pyrrolopyrrole and quinacridone pigments and/or its solid solutions. Said derivatives are highly suitable for the synthesis of quinacridone pigments in their specific crystal modifications such as the alpha, beta or gamma quinacridone, 2,9-dichloroquinacridone, 2,9-dimethylquinacridone, 4,11-dichloroquinacridone and solid solutions thereof. The inventive 6,13-dihydroquinacridone derivatives are particularly effective, when they are completely or partially soluble in the reaction media in which the pigment is being synthesized.
Accordingly, a further embodiment of the present invention concerns a process for the preparation of a direct pigmentary diketopyrrolopyrrole or quinacridone pigment or a solid solution thereof comprising the step of synthesizing said pigment or solid solution in the presence of 0.5 to 8 percent by weight of a 6,13-dihydroquinacridone of formula I, based on the pigment being synthesized.
Without limiting this invention to any particular theory, it is believed that the inventive 6,13-dihydroquinacridone derivatives molecule is adhered to the synthesized pigment molecule and by this is directing the crystal growth and crystal phase. The term xe2x80x9cdirecting the crystal growthxe2x80x9d refers to controlling the synthesis of pigment particles having a pigmentary size as well as directing the growth of the crystals to generate particles of a specific desirable shape such as platelet, needle, cubic, leaflet, rod and other geometric forms, in a desirable crystal phase. The effect can be influenced by the chemical structure of the organic pigment, the selection of the reaction media, the pigment synthesis procedure, the concentration and the chemical structure of the inventive 6,13-dihydroquinacridone derivatives.
Under circumstances in which the reaction media of the pigment to be synthesized is oxidative, the inventive 6,13-dihydroquinacridone derivative may be partially or completely oxidized to the corresponding quinacridone derivative during the pigment synthesis. Therefore, the inventive 6,13-dihydroquinacridone derivatives are particularly useful for the quinacridone pigment synthesis when the quinacridone pigment is obtained by the oxidation of the corresponding 6,13-dihydroquinacridone as described, for example, in U.S. Pat. No. 5,840,901.
During the isolation of the pigment, for example in the filtration step, these 6,13-dihydroquinacridone derivativesxe2x80x94when soluble in the reaction mediaxe2x80x94can be washed out and if desirable, be recollected from the filtrate or wash liquid. Typically, these compounds are partially left on the pigment surface and can have additional benefits. Such benefits are, for example, improved pigment properties such as rheological properties, dispersibility and wetting behavior, flocculation resistance and improved heat stability.
Additionally, it has been found that phthalimidomethyl dihydroquinacridone, previously described as a pigment dispersant, can be an effective pigment particle growth controller and pigment crystal phase director.
In certain cases, it is advantageous to use the inventive 6,13-dihydro-quinacridone derivatives in mixture or in combination with other additives including known pigment particle growth inhibitors such as, for example, the compounds described in Copending U.S. Provisional Patent Application entitled xe2x80x9cPIGMENT PARTICLE GROWTH AND/OR CRYSTAL PHASE DIRECTORSxe2x80x9d, or phthalimidomethyl-, imidazolmethyl- or pyrazolmethyl-quinacridone, pigment sulfonic acids, specific polymers or other optional ingredients such as wetting agents, surfactants, defoamers, antioxidants, UV absorbers, light stabilizers, plastisizers, or general texture improving agents and so forth. Any such additional additives may be used as long as such additives are stable under the pigment synthesis conditions and have no negative impact on the final pigment properties or the environment. Generally, such additives can be added in a concentration of 0.1 to 25 percent, preferably 0.2 to 15 percent and most preferably 0.5 to 8 percent by weight, based on the weight of pigment to be synthesized. The resulting pigment/additive mixture can be used in any conventional pigment application, such as in the formation of paints, inks, color filters, fibers, paper or textiles.
Suitable polymers are, for example, polyacrylic acid, polymethacrylic acid, polyvinylpyrrolidone, polymaleic anhydride, polyurethane, polyvinylether, polyvinylalcohol, polyalkylene glycol, polyethylene oxide, cellulose derivatives, polyimine, polyvinylpyridine, or copolymers such as copolymers of acrylic acid with styrene, acrylonitrile, vinylacetate, vinylphosphonate, vinylpropionate, vinylchloride, itaconic acid or maleic anhydride, or a mixture thereof, or polymeric derivatives like ethoxylated or propoxylated fatty amines such as ethoxylated cocoalkyl, oleyl or soy-alkyl amines; ethoxylated or propoxylated fatty quaternary salts such as ethoxylated cocoalkyltrimethyl ammonium chloride; ethoxylated fatty amides such as ethoxylated oleamides; alkyl-, cycloalkyl- or alkylaryl-oxypoly(ethylenoxy)ethanol, cycloalkyloxypoly(ethylenoxy)laurate or oleate, polyethylene glycol 400 laurate or oleate, alkyl-, cycloalkyl- or alkylaryl-poly(ethylenoxy)carboxylate or phosphonate.
Suitable surfactants belong to the group of anionic surfactants like for example the alkylbenzene- or alkylnaphthalene sulfonates, alkylsulfosuccinates or naphthalene formaldehyde sulfonates; the group of cationic surfactants like for example quaternary salts such as benzyl tributyl ammonium chloride; or the group of nonionic or amphoteric surfactants like the polyoxyethylene surfactants or alkyl- or amidopropyl betaines, respectively.
Suitable texture improving agents are for example fatty acids such as stearic acid or behenic acid, and fatty amines such as laurylamine and stearylamine. In addition, fatty alcohols or ethoxylated fatty alcohols, polyols such as aliphatic 1,2-diols or epoxidized soy bean oil, waxes, resin acids and resin acid salts.
Suitable UV stabilizers are for example the known benzotriazol derivatives known under the trade name TINUVIN or CIBA Fast H Liquid an aryl sulfonated benzotriazol, both being products of Ciba Specialty Chemicals Corporation.
Due to the ability to act as an antiflocculant as well as an excellent particle growth inhibitor and phase director, the inventive 6,13-dihydroquinacridone derivatives can generally be used in the pigment finishing, pigment treatment, or pigment application such as an additive during the pigment dispersion step in bead mills, extruder, calendar and so forth, as well as during pigment synthesis.
Pigment finishing processes in which the inventive 6,13-dihydroquinacridone derivatives can be used are for example the known kneading, solvent or aqueous milling processes.
Particularly effective are the inventive 6,13-dihydroquinacridone derivatives when present in pigment finishing processes in which a pigment crude is premilled and after treated in an organic solvent, a process as described for example in the U.S. Pat. Nos. 5,194,088 and 2,857,400.
The following examples further describe the embodiments of the invention, but do not limit the scope of the invention. In the examples, all parts are by weight unless otherwise indicated.